1. Field of the Invention
The present invention relates to a frequency jamming analysis and transmission selection system; and more particularly, to an improved jamming analysis and transmission selection system for radar using a surface acoustic wave device to detect interfering frequencies that may be located in the vicinity of the radar's allowed transmit frequencies.
2. Description of the Prior Art
In order to transmit radar pulses and receive the echoes therefrom in an environment where other radar systems are operating; or where jamming of the transmitted frequencies may occur, it is customary to provide a radar system with the capability of transmitting and receiving selected ones of a plurality of distinct frequencies over a predetermined bandwidth. To prevent the particular frequencies that are interfering with or jamming the radar system, from preventing proper operation thereof, there has been provided what is termed a jamming analysis and transmission selection system (JATS). The typical JATS capability provides for receiving and analyzing any interfering signals during a portion of the time period between transmitted radar pulses; or in other words during a portion of the interpulse periods. Specifically, such a system utilizes the frequency generator of the transmitter to interrogate in sequence a plurality of predetermined frequencies over which the radar system is capable of transmitting; and then causes the same frequency generator of the radar transmitter to transmit pulses of a particular frequency which has demonstrated little or no noise or jamming. Such a system places a heavy burden on the frequency generator of the transmitter thus tending to adversely affect its stability. Such a system consumes approximately sixty to one hundred microseconds of each interpulse period for both interrogation and shifting to a new frequency. One proposed solution is to use a separate frequency generator for analyzing the anticipated frequencies; but does not appear feasible for many applications because of its size, complexity, and relative cost.
Thus, it is desirable to provide an improved JATS system that does not utilize the frequency generator of the transmitter to interrogate the transmit band, and yet is relatively simple in configuration and uncomplicated in construction.